The present invention relates to chairs, and more particularly to a chair arm assembly which is vertically adjustable and rotatable with respect to a chair seat.
The chair design industry has heretofore provided a wide variety of chairs for the office environment which are ergonomically designed for the comfort of the user. These chairs include various adjustment mechanisms to accommodate the needs of particular users. The chairs may, for example, include vertically adjustable seat height mechanisms, swivel and tilt mechanisms and reclining back mechanisms. Some chairs provided arm assemblies which are adjustable vertically and horizontally relative to the chair seat.
Typically, height adjustable chair arms are plastic assemblies which fit over plastic and metal supports. The plastic and/or metal supports provide the structural strength for the chair arm assembly. These adjustable chair arms typically utilize screw fastening systems and punched or slotted metal tube or brackets to provide engagement for the height adjustment mechanism. Many height adjustable arms having a plastic height adjustment assembly on a metal substructure encounter problems with wobble and may rattle or feel loose, particularly at the top of the height adjustment range. In addition, in many of these height adjustment mechanisms the actuation of the height adjustment feature requires the user to remove his hand from an at-work position in order to move a lever or other actuating device to adjust the chair arm.
A need exists for a chair arm assembly which is adapted for vertical and rotational height adjustment, which permits a wide latitude in vertical and rotational positioning of the chair arm assembly, which is relatively easily manufactured, which is reliable in operation and which provides a wide variety of adjustable positions for the user.
It is, therefore, an object of the invention to provide an chair arm assembly which may be adjusted vertically and rotationally, and which may be optionally pivoted forward and backward.
It is a further object of the invention to provide an adjustable chair arm assembly in which the height adjustment mechanism utilizes a plastic collet with an internal threaded surface providing plastic-on-plastic engagement for ease of use and positive engagement of the locking mechanism.
It is a further object of the invention to provide an adjustable chair arm assembly which utilizes a split plastic sleeve for locating the arm assembly on a metal support tube and eliminating bearing surface wobble.
It is a further object of the invention to provide a spring actuated rotational device which permits the chair arm assembly of the invention to move backward as the chair is pushed close to a desk or other fixed surface, and further, to enable the user to retract the chair arms so that they are aligned approximately with the incline of the back of the chair, thereby making the chair essentially "armless."
It is a further object of the invention to facilitate the assembly of the arm to a chair frame built of steel tube produced by a chair manufacturer, thus enabling flexibility of design in terms of tube shape and orientation, without necessitating redesign of the arm. Thereby, enabling the chair manufacturer to employ a set of components which may be fitted to, and integrated with, a variety of chair frame designs, without the need of a separate metal substructure.
It is yet another object of the invention to provide an adjustable chair arm assembly which permits the entire arm assembly to swivel on the metal support tube without disengagement of the height adjustment locking mechanism.